A turbomolecular vacuum pump can be used to establish vacuum conditions in a vacuum chamber. In certain contexts, the vacuum chamber or its contents can be extremely sensitive to vibrations caused by a pump rotor of the vacuum pump. For instance, the vacuum chamber can be extremely sensitive to vibrations when used in the manufacture of electron microscopes or in the testing and repair of masks for the manufacture of integrated electronic circuits.
To reduce transmission of mechanical vibrations from the vacuum pump to the vacuum chamber, vacuum pumps are generally equipped with a vibration damper interposed between the vacuum pump and the vacuum chamber.
In certain conventional structures, a vibration damper has a first flange for connection to the vacuum chamber, a second flange for connection to the vacuum pump, a flexible bellows made of steel for ensuring vacuum tightness and structural resistance of the damper to torsion, and one or more components made of rubber and arranged around the bellows to ensure damping of the vibrations generated by the vacuum pump. Such dampers can generally attain damping factors on the order of 10 to 100, which can be insufficient for applications demanding higher precision.
To improve the damping factor and to obtain an effective vibration damping at several frequencies, two dampers can be used in series. The two dampers can be connected by an annular member of considerable mass, such as a steel annular member. The arrangement of the mass between the two dampers allows a vibration damping system to be modeled as a two-pole transfer function and enables effective vibration damping at different frequencies. For instance, it is possible to obtain vibration damping both at a rotation frequency of the pump rotor and at a rotation frequency of a cage of bearings on which a rotation axis of the vacuum pump is mounted. The double damper can also increase the damping factor of the vacuum pump up to values on the order of 103.
These double dampers, however, have various drawbacks. For instance, in both single and the double dampers, using different members to ensure vacuum tightness (the bellows) and to achieve vibration damping and ensure structural rigidity (the rubber member(s)) entails a high number of components and, consequently, considerable production costs and high risks of breaking or malfunction. Moreover, although the single dampers give an unsatisfactory damping factor, the double dampers tend to have large axial sizes, making them unsuitable for applications requiring compactness. Moreover, low conductance resulting from a large axial size can reduce the actual pumping speed of the pump/damper system.